1. The Field of the Invention
The present invention relates generally to systems and methods for determining the authenticity of objects. More particularly, the present invention is related to systems and methods for automatically verifying the authenticity of an item by scanning for a security feature having predetermined spectral reflectance characteristics.
2. The Relevant Technology
In modem society, various conventional methods are utilized to trade goods and services. There are, however, various individuals or entities that wish to circumvent such methods by producing counterfeit goods or currency. In particular, counterfeiting of items such as monetary currency, banknotes, credit cards, and the like is a continual problem. The production of such items is constantly increasing and counterfeiters are becoming more sophisticated, particularly with the recent improvements in technologies such as color printing and copying. In light of this, individuals and business entities have a desire for improved ways to verify the authenticity of goods exchanged and/or currency received. Accordingly, the methods used to prevent counterfeiting through detection of counterfeit articles or objects must increase in sophistication.
Methods used to scan currency and other security items to verify their authenticity are described in U.S. Pat. Nos. 5,915,518 and 5,918,960 to Hopwood et al. The methods described in the Hopwood patents utilize ultraviolet (UV) electromagnetic radiation or light sources to detect counterfeit currency or objects. Generally, the tested object is illuminated by UV light and the resultant quantity of reflected UV light is measured by way of two or more photocells. The quantity of UV light reflected from the object is compared against the level of reflected UV light from a reference object. If the reflectance levels are congruent then the tested object is deemed authentic.
The methods in the Hopwood patents are based on the principle that genuine monetary notes are generally made from a specific formulation of unbleached paper, whereas counterfeit notes are generally made from bleached paper. Differentiation between bleached and unbleached paper can be made by viewing the paper under a source of UV radiation. The process of detection can be automated by placing the suspect documents on a scanning stage and utilizing optical detectors and a data analyzing device, with associated data processing circuitry, to measure and compare the detected levels of UV light reflected from the tested document.
Unfortunately, there are many problems with UV reflection and fluorescence detection systems, that result in inaccurate comparisons and invalidation of genuine banknotes. For example, if the suspect object or item has been washed, the object can pick up chemicals which fluoresce and may therefore appear to be counterfeit. As a result, each wrongly detected item must, therefore, be hand verified to prevent destruction of a genuine object.
Other conventional methods to detect counterfeit objects utilize magnetic detection of items which have been embossed or imprinted with magnetic inks, and/or image verification of images on the object. Unfortunately, magnetic inks are available to counterfeiters and can be easily applied to counterfeit objects, and image verification systems can be fooled by counterfeit currency made with color photocopiers or color printers, thereby reducing the effectiveness of these anti-counterfeiting approaches.
Other verification methods utilize the properties of magnetic detection to detect the electrical resistance of items which have been imprinted with certain transparent conductive compounds. These methods are, however, relatively complicated and require specialized equipment which is not easily available, maintainable, or convenient to operate, particularly for retail establishments or banks that wish to quickly verify the authenticity of an item.
Various items such as banknotes, currency, and credit cards have more recently been imprinted or embossed with optical interference devices such as optically variable inks or foils in order to prevent counterfeiting attempts. The optically variable inks and foils exhibit a color shift which varies with the viewing angle. While these optical interference devices have been effective in deterring counterfeiting, there is still a need for an accurate and convenient measuring system to verify that an item is imprinted with an authentic optical interference device.
With current advances in technology, new techniques are needed to battle a counterfeiter""s ability to fabricate counterfeit objects. Accordingly, there is a need to provide authentication systems that extend the arsenal available to governments, business retailers, and banks to verify the authenticity of an item.
A primary object of the present invention is to provide systems and methods for authenticating an object which should have an optical interference device as a security feature.
Another object of the present invention is to provide systems and methods for detecting the spectral characteristics associated with an optical interference device such as a color shifting pigment, ink, or foil used for anti-counterfeiting purposes.
Yet another object of the present invention is to provide systems and methods which are capable of detecting the spectral shape or degree of spectral shift as a function of angle for items which have been imprinted or embossed with a color shifting security feature.
Still yet another object of the present invention is to provide systems and methods which are capable of detecting and analyzing the dispersion pattern of light reflected from an optical interference security feature.
A further object of the present invention is to provide a system for accurate determination of the authenticity of items which requires only minimal upgrades of existing verification scanning systems.
Still a further object of the present invention is to provide systems and methods which are capable of using various wavelengths of electromagnetic radiation to authenticate an optical interference security feature.
To achieve the forgoing objects and in accordance with the invention as embodied and broadly described herein, systems and methods are provided for automatically verifying the authenticity of an object by scanning for an optical interference security feature in the form of an optical interference device, such as a color shifting device having predetermined spectral reflectance or transmittance characteristics. Various objects such as currency, banknotes, credit cards, and other similar items imprinted or embossed with an optical interference device can thereby be authenticated.
A color shifting security feature exhibits both a characteristic reflectance spectrum and a spectral shift as a function of viewing angle, which can be utilized by the verification systems of the invention to determine the authenticity of an object. A verification system of the invention can be automated by placing the items to be verified on a transport stage which moves the items in a linear fashion for scanning.
The verification systems of the present invention generally include an optical system, a transport staging apparatus, and an analyzing device. The optical system includes one or more light sources that are capable of generating either narrow band or broadband light beams. Cooperating with the light sources is the transport staging apparatus, which is configured to position the object such that one or more of the light beams strike a portion of the object where a security feature should be located. The analyzing device receives the light beams reflected or transmitted from the object and the security feature, and is adapted to analyze the optical characteristics of the light beams reflected or transmitted by the object at varying angles and/or wavelengths to verify the authenticity of the object.
In one method for verifying the authenticity of an object according to the present invention, at least one light beam at a first incident angle is directed toward an object to be authenticated. The object is positioned such that the light beam is incident on a portion of the object where an optical interference security feature should be located. The light beam is directed from the object along one or more optical paths, such as by reflection or transmission, and one or more optical characteristics of the light beam are analyzed to verify the authenticity of the object. The optical characteristics can be analyzed by comparing the spectral difference between two light beams reflected or transmitted at different angles from the object against a reference spectral shift, or by comparing the spectral shape of at least one light beam reflected or transmitted from the object against a reference spectral shape.
These and other aspects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.